A flow of fluid, e.g. steam or gas, can be provided to a turbine as a source of power or fuel. Such turbines find use in a variety of applications, for example in electrical power plants.
To regulate the amount of fluid flowing to the turbine, it is common to provide a valve in a fluid line leading to the turbine. A control circuit, which incorporates e.g. a closed loop controller or an open loop controller, supplies a control signal, in response to which control signal the valve opens to a corresponding degree.